Hi,
I have assigned a global shortcut to opera from system settings -> Input Actions.
If I put command as just opera it launches with correct launch feed back icon(opera one).

But when invoked with an argument "opera --notrayicon" that instead of opera icon for launch feed back I get an ugly icon resembling a setting one.

How can I get same launch feed back icon for both cases?

Have you tried logging out and back in again to ensure the changes are fully propagated?
Also, try rebuilding the Sycoca: "kbuildsycoca4 --noincremental"

Restarting or rebuilding the Sycoca did not help. Guess kde is reading a different icon when invling opera with an argument.

If you create a menu entry with the same command parameter as that action, and set the icon there does it work?

If I create a menu entry with the sama paramaters. I the icon I set to the menu entey appears as tha launch feed back one.

I found a work around if in the system settings I point the command to the .desktop file I created in the menu then it works fine.